The present invention relates to a chuck, particularly for machine tools for centering and locking a workpiece to be machined.
Chucks for machine tools are known which are constituted by a frame which supports a table on which the workpiece to be machined is positioned; on the face of the table intended to face the workpiece to be machined there are defined first sliding seats which extend radially from the center of the table and accommodate workpiece centering means, which are controllably movable towards or away from the center of the table and are intended to contact portions of the workpiece arranged above the table. Also on the face of the table directed towards the workpiece to be machined there are defined second sliding seats which, like the first sliding seats, extend radially from the center of the table and accommodate workpiece locking means controllably movable towards or away from the center of the table from a first position spaced from the portions of the workpiece to be contacted to a second position proximate to the portions of the workpiece to be contacted. The locking means, as well as in a radial direction, are also controllably movable in a direction substantially perpendicular to the face of the table directed towards the workpiece from a release position, in which the locking means are disengaged from the workpiece, to an engagement position in which the locking means are engaged with the workpiece.
Both the centering means and the locking means are constituted by sliders which are slideably accommodated respectively in said first sliding seats and in said second sliding seats and have portions protruding from the table and intended to contact portions of the workpiece to be machined so as to position it correctly on the table and couple it rigidly thereto.
Such known types of chucks, though allowing a precise centering of the part to be machined and its effective locking to the table, have some disadvantages.
In fact, to obtain the movement of the centering means and of the locking means along the table, two separate control systems are generally used which complicate its execution, unavoidably raising its production costs.